PSI - Issue 18

Matus Margetin et al. / Procedia Structural Integrity 18 (2019) 663–670 Matus Margetin at al / Structural Integrity Procedia 00 (2019) 000–000

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Matake criterion Matake (1977) same as McDiarmid proposed that fatigue damaging under multiaxial loading is controlled by shear stress amplitude and that critical plane is the plane with maximal shear stress range. But he suggests that material parameter (in his case k ) should be obtain from two fatigue experimental sets with different stress stats (for example axial test and torsion test). Then his criterion for final fatigue lifetime estimation has following formulation: ���� � ��� ��� � � ′ ��� � � � � (4) Where coefficient k mat is defined as: ��� � � � ��� � ��� � � (5) In the case of two plane with identical shear stress range the critical plane is that with higher maximal normal stress. Again figures 3 show relative damage as a function of plane orientation for both material parameters from table 1 in case of pure axial and pure torsion loading.

Fig. 3. Damage distribution corresponding to Matake criterion as a function of plane orientation (a) S355; (b) C55.